Sound reproducer



June 30, 1931. -w, JONES 1,812,634

SOUND REPRODUCER Filed June 23, 1928 //v l/EN TO/P Manna-N C. Jon/5 A 7' TURN/F) Patented June 30, 1931 UNITED STATES PATENT OFFICE WARREN C; JONESfOF. FLUSHING, NEW YORK, ASS IGNOR TO BELL TELEPHONE LAB- ORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK SOUND REPROD'O'CER Application filed June as,

' structure of sufiiciently low mass and stiifness to 'meet the requirements for a playback when comparatively soft recording material is used.

A needle suitable for this purpose should be sufiiciently light and stiff that its length is the controlling factor in reducing the needle point mass; it should also be of a permanentor semi-permanent character and ada pted for ready-attachment -.to the associated parts without the addition of unnecessary masses to the moving structure,

In the drawings Fig. 1 is a sectional view of a reproducer embodying this invention. Fig. 2 is a perspective view of a needleshow ing the method of attachment to the diaphragm. i

Referring'to 1 the reproducer 1 is preferably of the bipolar electromagnetic type as shown and similar. to that disclosed in Patent 1,746,730, granted to me February 11, 1930, in which the diaphragm 2 forms a flexible closure for the container of the viscous matter 3. The diaphragm also con- Y stitutes a rocking support for the armature 4 which greatlystifiens the diaphragm in one direction but 'perinits substantially free flexing in the other. I

In the present invention, however, the

stylus holder is eliminated and the needle 4 5 is fitted with a threaded base member 6 which directly engages the threaded stud 7 projecting from the armature.

One form of needle which has been found suitable for play-back purposes consists of a conical shell of nickel about 1" long and sufliciently thin that its mass effective at the needle point is about .010 gms. Such a needle may be made from thin sheet material and fitted with a suitable point but it has been found preferable to 'electroform these 1928. Serial No. 287,722.

needles on a suitable mandrel as, described in Patent No. 1,733,608, granted to WV. G. Knox, et al., Oct. 29, 1929.

By contouring the point of this cone to fit the record grooves and then electro-depositing on it a thin layer of chromium, a needle of semi-permanent character is obtained. When it becomes necessary the needle may be replaced very easily without dismantling the reproducer due to the spe cial construction already described.

l Vhat is claimed is: p

1. A reproducer needle comprising a conical shell of metal with a hard metal surface at its point and a mounting member at its base.

2. A reproducer needle comprising a hollow conical shell of nickel, fitted with amounting member and chromium plated and contoured at its point to fit a record groove.

3. A stifi' reproducer needle having a length of the order of one inch and an effective needle-point mass of the order of .010

grams. i

.4. A reproducer needle comprising a hollow cone of metal having a length of the order of one: inch and an effective needlepoint mass ofthe order of .010 grams. a In witness whereof, I hereunto subscribe my'name this 21st day of June, 1928.

' WARREN C. JONES. 

